


Conservation and Entropy

by Amimia



Category: Kuroshitsuji | Black Butler
Genre: Canon - Manga, Canon-Typical Violence, Drama, F/M, Gen, Puella Magi Madoka Magica Crossover, kind of
Language: English
Status: Completed
Published: 2014-04-04
Updated: 2014-04-04
Packaged: 2018-01-18 04:25:55
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,831
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1415053
Author URL: https://archiveofourown.org/users/Amimia/pseuds/Amimia
Summary: <blockquote class="userstuff">
              <p>She is his fiancé, and she swears to save him, no matter what the cost. "What better way to break a contract than to make a stronger one?"</p>
            </blockquote>





	Conservation and Entropy

She's at the wrong place at the wrong time.

She'd been worried about Ciel, and as much as she hated being uncute in front of him, her fiancé, she would do anything to protect him.

And so she barges in and sees all the blood blood blood and the mangled corpses and the manic look in Sebastian's eyes and the cold expression on Ciel's face that suggests he's seen this a million times before and bloody hell he probably has.

They both turn to look at her and their eyes _their eyes_ their eyes. Sebastian's are bright and glowing and red _red_ red and his pupils are slit like a cat's. They do not bear the same quiet look of amusement that she is used to, oh no, they are mad, wild like an animals, so very not-human.

Ciel does not have his eyepatch but there is no empty socket or sealed eyelid and the scar she expects is not rough and long and puckered, oh no, it has five perfect points and it glows violet in the darkness.

It does not take long for her to piece the truth together. She supposes she always knew, subconsciously. She knew there was no way fragile little Ciel could survive the inferno that killed his parents and destroyed all he knew on his own. She knew in that there was something strange about that black _black_ black butler that came from nowhere to offer a life of devotion to an orphaned little boy. She knew in the way the man made the hair on the back of her neck stand on end whenever he was in her presence. She knew in the way that butler finished chores a little too quickly and made dishes a little too perfectly and accomplished tasks a little too impossible. And she really should have known in the way the butler stood in the pool of the blood of the undead in a sinking ship, smiling politely and offering a hand to his unfazed master.

And now she knows in the way Ciel's eye matches Sebastian's hand.

Usually they'd kill whoever knew too much, but they make an exception for her.

vvv

She spends the next few weeks doing nothing but research.

She reads everything she can get her hands on; literature from the library, pamphlets from the old cult down the street, bibles and holy books in their original Hebrew or Latin, scrolls borrowed from museums and books sold on the black market. She speaks to everyone she can; witch doctors, wiccans, priests, nuns, fortune-tellers and cultists and even that odd fellow in the undertaker business that finds the strangest things funny.

Nothing and no one can give her the answer she's looking for.

So she cries as she pores over " _Daemons and Faerie Folk_ ” for the third time, because maybe she just wasn't reading close enough the first two times and this one is the one that will reveal the loophole she needs, the answer she cannot find. 

She has not slept in days and her eyes are swollen with tears and it's pouring outside the dusty library window, so maybe she imagines the shadow behind the windowpane, but maybe she doesn't, because a deceptively innocent, childlike voice echoes into the room.

_"What better way to break a contract than to make a stronger one?"_  

vvv

It's exhilarating and terrifying when she goes on her first hunt, her expensive mary-janes clacking on cobbled night darkened roads and summoning her new powers to vanquish her prey and feed her strength.

She has no delusion over what she really is.

vvv

Ciel allows her to tag along more often, because she's proven more than capable of defending herself, even against not-quite-human antagonistic nasties. And it's not as though he has anything to hide anymore; she knows his secret but he trusts her to tell no one as much as he's began to trust her with his life.

And of course, she has no longer has any desire to hide her "uncute" side from him, for what good is cuteness when you're dead? 

vvv

The years pass and things have changed. Ciel's jaw is sharper, his shoulders broader; he no longer has the look of a porcelain doll, but a lean muscled man. Yet he is still beautiful, with shiny blacksilver hair and a sapphire blue eye and smooth pallid skin and the villains of the underground with the more unsavory tastes still make their unwanted advances.

He is so beautiful it makes her want to cry, because he is hopelessly broken and twisted but you wouldn't know it from the outside, because on the outside he looks as though he's been blessed by God. Though, really, that couldn't be farther from the cold black truth.

Her features have changed as well; her body is curved in all the right places, her hips round and her chest plump. She has become more fragile in appearance, covered in layers of skirts in petticoats, and it's a wonderful thing to use to their advantage, because both Ciel and Sebastian know there are muscles hidden under her sleeves, her corset, and her stockings, but everyone else is none the wiser. It's quite frustrating to Ciel, because one day his Lizzy was a cute little girl, and the next she was pretty young woman, and that was something very difficult for any teenage boy to deal with.

She does not greet him with a hug-tackle anymore, nor does she hug him or touch him much at all. He'd written it off as her growing maturity, but he began to notice she seemed less cheerful and more solemn. When he asks, her only answer was a quiet smile.

She has become a constant in his life; she is the watchdog's guard dog, a force to be reckoned with. Ciel's aim with a pistol has improved, but despite the changes to his body his is still, at his core, frail and sickly and unable to defend himself in dire situations. But he doesn't need to; Lizzy has become almost as attuned to his distress as Sebastian, and she is always ready with blades sharpened and glinting.

The first human she'd killed was a tax collector with ties to the underground and a strong desire to be left alone. His fate was sealed the moment he pointed his gun at the heir of the Phantomhive family. She'd cried then; the weight of taking the life of another human being crashing down on her. Ciel talked her through it, telling her it got easier as time went on, and he was right; she hates it, to be sure, but there was no point in hesitation as long as she was protecting Ciel.

She always uses her heirloom blades, sabres passed down in her family for generations. She never uses her unnatural powers around Ciel.

vvv

She loves Ciel with every fiber of her being, and the mere thought of anyone hurting him fills her with anger. She channels her fury through her blades, unsatisfied until they are blood soaked and her Ciel is safe.

Her Ciel.

They are on the best terms they have been since they were children. They actually have conversations and comfort each other after particularly harsh missions and genuinely enjoy each other's company, but he will never be hers.

She loves him so much, she always has, but for once in her life she prays to God and his angels that he does not love her back.

vvv

 She doesn't sleep much and she wonders if she even needs to anymore. She spends her days as a proper heiress and her nights as a vengeful guardian angel.

She's just like those walking cadavers on the Campania, she thinks. But she won't let that black _black_ black demon crush her skull between his hands. 

vvv 

There is something about this case that he is hiding from her, but she doesn't know why. Hadn't she earned his trust by now?

vvv

Sebastian doesn't give her a chance to take a bite out of these thugs. His fighting style is wilder, more violent, less clean than usual. Elizabeth just watches, disgusted. 

She turns to Ciel, and he looks resigned. Before she can say anything, he speaks.

He tells her she should leave.

She turns back; the thugs are a pile of bloody flesh and bone and the butler is advancing and he looks manic-even more than he is normally after a kill.

Fear settles in her stomach.

Her fiancé sets his jaw.

The murders of his parents are dead, his butler states.

She immediately steps in front of him - her fiancé, her Ciel - blades drawn and ready. 

The boy protests and the demon laughs.

It transforms into a sight that hurts her eyes, black _black_ black and feathered and sharp, but she stares back in defiance. It cannot have him. It will not.

And she transforms too.

They rush at each other as Ciel yells, clashing with sparks flying.

Their fight is a desperate dance, the demon a flurry of black hungry rage and the girl a spiral of multicolor determination.

 vvv

The light is so bright it burns Ciel's eyes, and the inhuman shrieking of the demon stabs at his ears. The air is full of energy, sparking and heavy.

And suddenly, it is silent and dark. 

The boy opens his eyes. He sees that the demon is gone from this world, perhaps gone from existence. He sees his fiancé turn to him on wobbly legs, her swords dropped with a clatter and her clothes transforming back in a flash of light. He doesn't realize, until he watches her fall to her knees, that he can see out of both eyes. 

vvv

She is bruised and bloody, but he still runs forward, falls into a kneel before her, and grabs her shoulders. He tells her she's amazing, smiling like he hasn't smiled since his parents died, and he tells her she did it, he doesn't deserve it but she freed him, now you can really be my wife, now we can really have children, now we'll live till we're old while serving the Queen.

She smiles up at him, tears flowing steadily down her face.

He quiets, glancing down at her face, then to her hands, folded in her lap, fingers closed around something. 

As he watches, her hands turn over and her fingers uncurl, revealing the most beautiful gem Ciel has ever seen. 

Intricately carved golden structures cradle an egg-shaped jewel that glows black _black_ black. There is a tiny speck of pink floating about, but the stormy darkness quickly swallows it.

Ciel looks up to Elizabeth's face. She stares back, sad smile unchanging. 

There is a _tik_ , and the boy looks down to see a small fracture in the gem. He looks back up at his fiancé in alarm.

"A soul for a soul," she whispers

The gem shatters and Ciel is alone. 

 

 

**Author's Note:**

> In case you don't know anything about Madoka Magica, there is a creature called Kyubey that makes deals with young girls in order to make them magical girls. In exchange for using their powers to hunt witches/wraiths (depending on the timeline) and indirectly creating energy for the creature to use through entropy, they are allowed one wish. However, their wish, no matter how selfless, usually has as many negative consequences as there are positive. In becoming a magical girl, the girl's soul is placed in a gem, and they must constantly defeat witches/wraiths in order to keep their gem clean. If they use up all their power, their gem turns black and shatters, which kills the girl. 
> 
> Elizabeth's wish was the power to save Ciel from his own contract and unfortunately, even magical girls have to follow the law of conservation.


End file.
